/* 
 * Digital Depth Economy Website
 * CSS Styles
 * Based on project brief requirements for research positioning
 */

/* Variables */
:root {
  /* Color Palette - Academic & Professional */
  --primary-color: #2c3e50;      /* Deep blue for academic credibility */
  --secondary-color: #3498db;    /* Accent blue for highlights */
  --tertiary-color: #ecf0f1;     /* Light gray for text on dark backgrounds */
  --text-color: #2c3e50;         /* Dark blue for text */
  --light-bg: #f5f7fa;           /* Light background */
  --dark-bg: #2c3e50;            /* Dark background */
  --highlight: #3498db;          /* Highlight color */
  --warning: #e74c3c;            /* Warning/error color */
  --success: #2ecc71;            /* Success color */
  --neutral: #95a5a6;            /* Neutral gray */
  --border-color: #dfe4ea;       /* Border color */
  
  /* Typography */
  --heading-font: 'Montserrat', sans-serif;
  --body-font: 'Open Sans', sans-serif;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --spacing-xl: 3rem;
  
  /* Border Radius */
  --border-radius-sm: 4px;
  --border-radius-md: 8px;
  --border-radius-lg: 12px;
  
  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-medium: 0.3s ease;
  --transition-slow: 0.5s ease;
}

/* Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--body-font);
  color: var(--text-color);
  line-height: 1.6;
  background-color: var(--light-bg);
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--heading-font);
  margin-bottom: var(--spacing-md);
  line-height: 1.3;
  font-weight: 700;
}

h1 {
  font-size: 2.5rem;
}

h2 {
  font-size: 2rem;
}

h3 {
  font-size: 1.75rem;
}

h4 {
  font-size: 1.5rem;
}

h5 {
  font-size: 1.25rem;
}

h6 {
  font-size: 1rem;
}

p {
  margin-bottom: var(--spacing-md);
}

a {
  color: var(--secondary-color);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--primary-color);
}

img {
  max-width: 100%;
  height: auto;
}

/* Container */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: var(--border-radius-md);
  font-weight: 600;
  text-align: center;
  text-decoration: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  border: none;
  font-family: var(--body-font);
}

.btn-primary {
  background-color: var(--secondary-color);
  color: white;
}

.btn-primary:hover {
  background-color: var(--primary-color);
  color: white;
}

.btn-secondary {
  background-color: var(--tertiary-color);
  color: var(--primary-color);
  border: 2px solid var(--primary-color);
}

.btn-secondary:hover {
  background-color: var(--primary-color);
  color: var(--tertiary-color);
}

.btn-tertiary {
  background-color: transparent;
  color: var(--secondary-color);
  border: 2px solid var(--secondary-color);
}

.btn-tertiary:hover {
  background-color: var(--secondary-color);
  color: white;
}

/* Header */
.header {
  background-color: white;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  position: fixed;
  width: 100%;
  top: 0;
  z-index: 1000;
}

.header-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-md) 0;
}

.logo {
  font-family: var(--heading-font);
  font-weight: 700;
  font-size: 1.5rem;
  color: var(--primary-color);
  display: flex;
  align-items: center;
}

.logo img {
  height: 50px;
  width: auto;
  margin-right: var(--spacing-sm);
}

.logo span {
  color: var(--secondary-color);
}

/* Navigation */
.nav-menu {
  display: flex;
  list-style: none;
}

.nav-item {
  margin-left: var(--spacing-lg);
}

.nav-link {
  color: var(--primary-color);
  font-weight: 600;
  position: relative;
}

.nav-link:after {
  content: '';
  position: absolute;
  width: 0;
  height: 2px;
  bottom: -4px;
  left: 0;
  background-color: var(--secondary-color);
  transition: width var(--transition-medium);
}

.nav-link:hover:after {
  width: 100%;
}

.nav-link.active {
  color: var(--secondary-color);
}

.nav-link.active:after {
  width: 100%;
}

/* Mobile Navigation */
.mobile-nav-toggle {
  display: none;
  background: transparent;
  border: none;
  cursor: pointer;
  font-size: 1.5rem;
  color: var(--primary-color);
}

/* Hero Section */
.hero {
  padding: 8rem 0 5rem;
  background-color: var(--dark-bg);
  color: var(--tertiary-color);
  position: relative;
  overflow: hidden;
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 800px;
}

.hero-title {
  font-size: 3rem;
  margin-bottom: var(--spacing-md);
}

.hero-subtitle {
  font-size: 1.5rem;
  margin-bottom: var(--spacing-lg);
  color: var(--tertiary-color);
  opacity: 0.9;
}

.hero-buttons {
  display: flex;
  gap: var(--spacing-md);
  margin-top: var(--spacing-lg);
}

/* Sections */
.section {
  padding: var(--spacing-xl) 0;
}

.section-title {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.section-title h2 {
  position: relative;
  display: inline-block;
  padding-bottom: var(--spacing-sm);
}

.section-title h2:after {
  content: '';
  position: absolute;
  width: 50%;
  height: 3px;
  bottom: 0;
  left: 25%;
  background-color: var(--secondary-color);
}

/* Cards */
.card {
  background-color: white;
  border-radius: var(--border-radius-md);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
  overflow: hidden;
  transition: transform var(--transition-medium), box-shadow var(--transition-medium);
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.card-img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.card-content {
  padding: var(--spacing-lg);
}

.card-title {
  margin-bottom: var(--spacing-sm);
}

/* Grid */
.grid {
  display: grid;
  gap: var(--spacing-lg);
}

.grid-2 {
  grid-template-columns: repeat(2, 1fr);
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-4 {
  grid-template-columns: repeat(4, 1fr);
}

/* Features */
.features {
  background-color: var(--light-bg);
}

.feature {
  text-align: center;
  padding: var(--spacing-lg);
}

.feature-icon {
  font-size: 3rem;
  color: var(--secondary-color);
  margin-bottom: var(--spacing-md);
}

/* Call to Action */
.cta {
  background-color: var(--primary-color);
  color: var(--tertiary-color);
  text-align: center;
  padding: var(--spacing-xl) 0;
}

.cta-title {
  margin-bottom: var(--spacing-lg);
}

/* Footer */
.footer {
  background-color: var(--dark-bg);
  color: var(--tertiary-color);
  padding: var(--spacing-xl) 0;
}

.footer-container {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--spacing-lg);
}

.footer-logo {
  font-family: var(--heading-font);
  font-weight: 700;
  font-size: 1.5rem;
  margin-bottom: var(--spacing-md);
  display: flex;
  align-items: center;
}

.footer-logo img {
  height: 40px;
  width: auto;
  margin-right: var(--spacing-sm);
}

.footer-links h4 {
  margin-bottom: var(--spacing-md);
}

.footer-links ul {
  list-style: none;
}

.footer-links li {
  margin-bottom: var(--spacing-sm);
}

.footer-links a {
  color: var(--tertiary-color);
  opacity: 0.8;
  transition: opacity var(--transition-fast);
}

.footer-links a:hover {
  opacity: 1;
}

.footer-bottom {
  margin-top: var(--spacing-xl);
  padding-top: var(--spacing-md);
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  text-align: center;
  font-size: 0.9rem;
  opacity: 0.7;
}

/* Utilities */
.text-center {
  text-align: center;
}

.text-right {
  text-align: right;
}

.mb-1 {
  margin-bottom: var(--spacing-xs);
}

.mb-2 {
  margin-bottom: var(--spacing-sm);
}

.mb-3 {
  margin-bottom: var(--spacing-md);
}

.mb-4 {
  margin-bottom: var(--spacing-lg);
}

.mb-5 {
  margin-bottom: var(--spacing-xl);
}

.mt-1 {
  margin-top: var(--spacing-xs);
}

.mt-2 {
  margin-top: var(--spacing-sm);
}

.mt-3 {
  margin-top: var(--spacing-md);
}

.mt-4 {
  margin-top: var(--spacing-lg);
}

.mt-5 {
  margin-top: var(--spacing-xl);
}

/* Responsive */
@media (max-width: 992px) {
  .grid-3, .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .footer-container {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  html {
    font-size: 14px;
  }
  
  .grid-2, .grid-3, .grid-4 {
    grid-template-columns: 1fr;
  }
  
  .hero-buttons {
    flex-direction: column;
  }
  
  .nav-menu {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background-color: white;
    box-shadow: 0 10px 15px rgba(0, 0, 0, 0.1);
    padding: var(--spacing-md) 0;
  }
  
  .nav-menu.active {
    display: flex;
  }
  
  .nav-item {
    margin: 0;
    text-align: center;
    padding: var(--spacing-sm) 0;
  }
  
  .mobile-nav-toggle {
    display: block;
  }
  
  .footer-container {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .footer-logo {
    justify-content: center;
  }
}

/* Academic/Research Specific Styles */
.research-badge {
  display: inline-block;
  background-color: var(--secondary-color);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: var(--border-radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
}

.research-phase {
  display: inline-block;
  background-color: var(--light-bg);
  color: var(--primary-color);
  padding: 0.25rem 0.75rem;
  border-radius: var(--border-radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  border: 1px solid var(--border-color);
}

.quote {
  font-style: italic;
  padding: var(--spacing-lg);
  background-color: var(--light-bg);
  border-left: 4px solid var(--secondary-color);
  margin: var(--spacing-lg) 0;
}

.quote-author {
  font-weight: 600;
  display: block;
  margin-top: var(--spacing-sm);
}

.research-card {
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-md);
  padding: var(--spacing-lg);
  background-color: white;
  margin-bottom: var(--spacing-lg);
}

.research-card-title {
  color: var(--primary-color);
  margin-bottom: var(--spacing-sm);
}

.research-card-subtitle {
  color: var(--neutral);
  font-size: 0.9rem;
  margin-bottom: var(--spacing-md);
}

.research-card-content {
  margin-bottom: var(--spacing-md);
}

.research-card-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--spacing-md);
  border-top: 1px solid var(--border-color);
}

/* Audience Pathways */
.audience-paths {
  display: flex;
  gap: var(--spacing-lg);
  margin: var(--spacing-xl) 0;
}

.audience-path {
  flex: 1;
  background-color: white;
  border-radius: var(--border-radius-md);
  overflow: hidden;
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
  transition: transform var(--transition-medium), box-shadow var(--transition-medium);
}

.audience-path:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
}

.audience-path-header {
  background-color: var(--primary-color);
  color: white;
  padding: var(--spacing-lg);
  text-align: center;
}

.audience-path-content {
  padding: var(--spacing-lg);
}

.audience-path-footer {
  padding: var(--spacing-lg);
  text-align: center;
  border-top: 1px solid var(--border-color);
}

/* Research Timeline */
.timeline {
  position: relative;
  max-width: 1200px;
  margin: 0 auto;
  padding: var(--spacing-xl) 0;
}

.timeline::after {
  content: '';
  position: absolute;
  width: 6px;
  background-color: var(--border-color);
  top: 0;
  bottom: 0;
  left: 50%;
  margin-left: -3px;
}

.timeline-item {
  padding: 10px 40px;
  position: relative;
  width: 50%;
}

.timeline-item::after {
  content: '';
  position: absolute;
  width: 25px;
  height: 25px;
  right: -12px;
  background-color: white;
  border: 4px solid var(--secondary-color);
  top: 15px;
  border-radius: 50%;
  z-index: 1;
}

.timeline-left {
  left: 0;
}

.timeline-right {
  left: 50%;
}

.timeline-left::after {
  right: -12px;
}

.timeline-right::after {
  left: -12px;
}

.timeline-content {
  padding: var(--spacing-md);
  background-color: white;
  position: relative;
  border-radius: var(--border-radius-md);
  box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
}

.timeline-date {
  font-weight: 600;
  color: var(--secondary-color);
  margin-bottom: var(--spacing-sm);
}

/* Accessibility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border-width: 0;
}

/* Focus styles for accessibility */
a:focus, button:focus, input:focus, textarea:focus, select:focus {
  outline: 2px solid var(--secondary-color);
  outline-offset: 2px;
}

/* Skip to content link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--primary-color);
  color: white;
  padding: 8px;
  z-index: 100;
}

.skip-link:focus {
  top: 0;
}